Perforating Gun and Method of Perforating a Well

ABSTRACT

A perforating gun ( 50 ) for use in a wellbore comprises a body ( 52 ) configured to be displaced within the wellbore, and first and second charge arrangements mounted on the body ( 52 ) and configured to be detonated independently of each other. In one embodiment the body ( 52 ) is configured to be moved axially within the wellbore between detonation of the first and second charge arrangements and at least portions of the first and second charge arrangements are provided within a common axial length of the body ( 52 ).

FIELD OF THE INVENTION

The present invention relates to a perforating gun, and in particular to a compact perforating gun for use in a wellbore. The present invention also relates to a method of perforating a well.

BACKGROUND TO THE INVENTION

In the oil and gas industry subterranean hydrocarbon bearing formations are intercepted by wellbores drilled from surface. Conventionally, a wellbore is supported and sealed using metal tubing, such as casing or liner tubing, which is run into an open drilled bore and then cemented in place. In many wellbore architectures the section of the wellbore which intercepts the hydrocarbon bearing formation is also sealed with liner tubing, which is eventually perforated to establish inflow from the formation. Perforation is typically achieved using a perforating gun which perforates the tubing string and cement at a target location by use of explosive charges.

A known perforating gun 10 is diagrammatically illustrated in FIG. 1, in use within a wellbore 12 which extends through a hydrocarbon bearing formation 14, wherein the wellbore 12 is sealed with a liner string 16 and annular layer of cement 18. The perforating gun 10 is run into the wellbore 12 on wireline 20 to the depth of the formation 14, and comprises a plurality of shaped charges 22 which are axially distributed, at appropriate circumferential phase angles, along a housing 24 of extended length. The gun 10 comprises a firing head 26 which in use detonates all the shaped charges 22 via a primer cord 28. The firing head may initiate detonation upon receipt of an appropriate signal, which may be transmitted through the wireline, for example by use of e-line. Detonation of the charges 22 results in a number of perforations 30 being created through the liner string 16, cement 18 and into the formation 14.

Known perforating guns, such as that illustrated in FIG. 1, are relatively long in order to maximise the length of the perforated zone to in turn maximise inflow. For example, some perforating guns may have a length which exceeds 15.25 m (50 feet), and provide a perforated zone in the region of 12.19 m (40 feet). However, the use of such long perforating guns may create adverse issues, such as on-site storage issues, difficulty in manipulating through the wellbore, which may include deviated sections, increased risk of failure of one or more charges or the like.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a perforating gun for use in a wellbore, comprising:

a body configured to be displaced within a wellbore: and

first and second charge arrangements mounted on the body and configured to be detonated independently of each other.

The body may be configured to be axially displaceable within a wellbore. The body may be configured to be axially displaceable between detonation of the first and second charge arrangements. In use, the first charge arrangement may be detonated at a first location within the wellbore, the body then moved to a second, different location within the wellbore with the second charge arrangement then detonated. This may permit the first and second charge arrangements to perforate different sections of the wellbore, which may in turn permit the perforating gun to be utilised to perforate extended axial lengths of a wellbore. That is, the perforating gun may be configured to perforate a length of the wellbore which exceeds the length of the body. This may therefore address adverse issues associated with known perforating guns which typically define extended lengths to ensure an appropriate region of a wellbore can be perforated. The perforating gun may define a compact perforating gun.

At least portions of the first and second charge arrangements may be provided within a common axial length of the body. The first and second charge arrangements may be configured to at least partially overlap in an axial direction relative to the body.

At least portions of the first and second charge arrangements may be confined to separate regions of the body. The separate regions of the body may be arranged side-by-side. The separate regions of the body may be defined by separate axially extending regions. For example, portions of the first and second charge arrangements may be aligned side-by-side along an axial length of the body. The separate regions of the body may be defined by separate axially extending segments of the body. The separate regions of the body may be defined by separate annular or cylindrical regions of the body. For example, portions of one charge arrangement may at least partially circumferentially circumscribe portions of the other charge arrangement. The first and second charge arrangements may be at least partially concentrically arranged, one inside the other, relative to the body.

At least portions of the first and second charge arrangements may be interspersed, for example provided in common regions of the body.

At least a portion of one or both of the first and second charge arrangements may be mounted on the body, for example on an outer surface of the body. At least a portion of one or both of the first and second charge arrangements may be mounted within the body, such as within a cavity formed within the body.

The body may be provided as a single component. The body may be provided by multiple components. Separate components of the body may be associated with separate charge arrangements.

The first and second charge arrangements may each comprise at least one charge. The charge may comprise an explosive material. The charge may comprise one or more projectiles. The charge may comprise a shaped charge, configured to focus the energy from explosion thereof in a predetermined manner. In embodiments of the invention one or both of the first and second charge arrangements may comprise a plurality of charges.

The perforating gun may comprise additional charge arrangements. Any additional charge arrangement may be similar or identical in form to one or both of the first and second charge arrangements.

The perforating gun may comprise first and second firing heads associated with the first and second charge arrangements, respectively. Each firing head may be configured to independently detonate a respective charge arrangement. Each firing head may be configured to detonate a respective charge arrangement via a primer cord arrangement.

One or both of the first and second firing heads may be mounted on or relative to the body. One or both of the first and second firing heads may be mounted remotely from the body.

The perforating gun may comprise a controller configured to control detonation of one or both of the first and second charge arrangements. The controller may be provided within a controller module. The controller may comprise a receiver configured to receive a signal from a remote location. The signal may be associated with detonation instructions. For example, the signal may comprise instructions to detonate one or both of the first and second charge arrangements. The receiver may be configured to receive a signal transmitted along a member extending between a remote location and the receiver. The member may comprise electrical wire, optical fibre, metal tubing or the like. The receiver may be configured to receive a signal transmitted wirelessly from a remote location, for example via wellbore fluids, subterranean strata or the like. The signal may comprise pressure pulses, pressure variations, vibrations, acoustic signals, electromagnetic radiation or the like. The receiver may be configured to receive one or more mechanical based signals, such as signals associated with one or a series of applied forces. The receiver may be configured to receive signals from a surface location. The receiver may be configured to receive signals from a downhole location.

The controller may comprise a timer configured to initiate detonation of one or both of the first and second charge arrangements following a predetermined elapsed time.

The timer may be started in response to a predetermined event, such as reaching a required depth, exposure to one or more predetermined conditions, such as pressure and/or temperature conditions, in response to receipt of a signal, or the like. The timer may be started in response to detonation of one of the first and second charge arrangements, such that the charge arrangements may be detonated sequentially, separated by a predetermined elapsed time. In this arrangement the body may be displaced within the predetermined elapsed time permitting different portions of a wellbore to be perforated by the first and second charge arrangements.

The controller may be mounted on or relative to the body. The controller may be mounted remotely from the body.

The perforating gun may be adapted or configured to be mounted on a displacement arrangement configured to move the perforating gun within a wellbore. The displacement arrangement may form part of the perforating gun.

The displacement arrangement may comprise an elongate member secured to the perforating gun, for example secured to the body of the perforating gun. The elongate member may extend between the perforating gun and a drive apparatus such that the drive apparatus may function to move the perforating gun via the elongate member. The elongate member may comprise wireline, slickline, tubing, coiled tubing or the like, or any suitable combination thereof. The elongate member may function to establish communication between the perforating gun and a remote location, such as electrical communication, fluid communication, optical communication, mechanical communication or the like. The elongate member may be configured to deliver one or more signals to and/or from the perforating gun. Such one or more signals may be associated with detonation instructions, status indicators or the like.

The displacement arrangement may comprise an autonomous displacement arrangement, such as an arrangement which includes an onboard drive apparatus. The displacement arrangement may comprise a downhole tractor.

The displacement arrangement may comprise a fluid actuated surface configured to receive a fluid force to displace the perforating gun along a wellbore. The fluid actuated surface may be configured to extend from the perforating gun towards a surface of a wellbore, with fluid pressure established within the wellbore causing displacement of the perforating gun. The fluid actuated surface may comprise one or more fins. In this arrangement the perforating gun may be configured to be pumped through a wellbore.

The perforating gun may be configured to be stored within a tool storage chamber. The perforating gun may be configured to be manipulated within a tool storage chamber to be configured between a storage position and a deployed position. The perforating gun may be configured to be coupled to a displacement arrangement when positioned within a deployed position.

The perforating gun may be configured to be provided in combination with a number of other tools to be deployed and/or retrieved within a wellbore. The perforating gun may be configured to be provided as part of an intervention system, such as a subsea intervention system.

According to a second aspect of the present invention there is provided a method of perforating a well, comprising:

locating a perforating gun having first and second charge arrangements mounted on a body within a wellbore; and

independently detonating the first and second charge arrangements.

The method may comprise axially displacing the perforating gun between detonation of the first and second charge arrangements. In this way, the first charge arrangement may be detonated at a first location within the wellbore, the body then moved to a second, different location within the wellbore with the second charge arrangement then detonated. This may permit the first and second charge arrangements to perforate different sections of the wellbore, which may in turn permit the perforating gun to be utilised to perforate extended axial lengths of a wellbore. That is, the perforating gun may be configured to perforate a length of the wellbore which exceeds the length of the body. This may therefore address adverse issues associated with known perforating guns which typically define extended lengths to ensure an appropriate region of a wellbore can be perforated. The perforating gun may define a compact perforating gun.

Features associated with the first aspect and defined and implied methods of use may apply within the method according to the second aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a known perforating gun;

FIG. 2 is a diagrammatic illustration of a perforating gun in accordance with an embodiment of the present invention;

FIG. 3 is a lateral cross-section of the perforating gun taken through line 3-3 in FIG. 2;

FIGS. 4 and 5 show sequential stages in operation of the perforating gun first shown in FIG. 2;

FIG. 6 is a diagrammatic cross-sectional representation of a perforating gun in accordance with an alternative embodiment of the present invention; and

FIG. 7 is a diagrammatic cross-sectional representation of a perforating gun in accordance with a further alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A diagrammatic illustration of a perforating gun, generally identified by reference numeral 50, in accordance with an embodiment of the present invention is shown in FIG. 2, and a lateral cross-section of the gun 50 through line 3-3 is shown in FIG. 3. The gun 50 comprises a body 52 which is mounted on wireline 54 to be displaced trough a wellbore (not shown). The gun 50 comprises first and second charge arrangements mounted on the body 52, wherein each of the first and second charge arrangements comprises a plurality of individual explosive charges 56, 58. In the exemplary embodiment shown the individual charges 56, 58 of the first and second charge arrangements are confined to respective separate regions 52 a, 52 b of the body 52, specifically respective halves of the body 52. However, in other embodiments the individual charges may be confined to different separate regions of the body, or may be interspersed with each other such that there are no defined separate regions.

As will be described in further detail below, the gun 50 is configured such that the first and second charge arrangements may be detonated independently of each other. As will also be discussed in detail below, the gun 50 may be moved between detonation of the first and second charge arrangements to perforate different sections of a wellbore.

The gun 50 further comprises a first firing head 60 associated with each charge 56 of the first charge arrangement via a primer cord 62, and a second firing head 64 associated with each charge 58 of the second charge arrangement via a further primer cord 66. Each firing head 60, 64 is configured to independently detonate the first and second charge arrangements.

The gun further comprises a controller 68 which is configured to control detonation of the charge arrangements. The controller 68 is configured to receive one or more signals, for example transmitted through the wireline 54, which signals carry detonation instructions. The controller 60 permits independent actuation of the firing heads 60, 64 in accordance with the detonation instructions.

Reference is now made to FIGS. 4 and 5 which show sequential stages of the use of the perforating gun 50 first shown in FIG. 2 within a wellbore. The wellbore is defined by a drilled bore 70 which extends through a formation 72 and which is supported and initially sealed by use of a liner tubing string 74 cemented in place by an annular layer of cement 76. The perforating gun 50 is run through the liner tubing string 74 on the wireline 54 until the required depth is reached, as demonstrated in FIG. 4. A detonation signal may then be transmitted from a remote location, for example from a surface location through the wireline 54, and received by the controller 68. In accordance with the detonation instructions the controller 68 may initiate the first firing head 60 to detonate the individual charges 56 of the first charge arrangement to create a first series of perforations 78 through the liner tubing 74, cement 76 and into the formation 72. Once the first series of perforations 78 is established the gun 50 may be displaced on the wireline 54 to a different location, as shown in FIG. 5, and the process repeated to detonate the individual charges 58 of the second charge arrangement to create a second series of perforations 80 at this different location. That is, a further signal may be transmitted via the wireline 54 which is received by the controller 68 which in turn initiates the second firing head 64 to detonate the charges 58 of the second charge arrangement.

The perforation gun 50 of the present exemplary embodiment may therefore permit a length of a wellbore to be perforated which exceeds the length of the gun itself. This may therefore assist to address adverse issues associated with known perforating guns which typically define extended lengths to ensure an appropriate region of a wellbore can be perforated.

As suggested above, the individual charges may be arranged within the body in different configurations to that shown in FIG. 2. Additionally, it should be noted that any suitable number of charge arrangements may be provided. For example, a perforating gun, generally identified by reference numeral 100, according to an alternative embodiment of the present invention is shown in FIG. 6. In this embodiment the gun 100 includes four separate charge arrangements mounted within a body 102 and each comprising individual charges 104, 106, 108, 110. The charge arrangements are confined to individual axially extending segments 102 a, 102 b, 102 c, 102 d of the body 102. In use, the perforating gun 100 may be operated in a four stage cycle to establish four separate sets of perforations.

In a further embodiment, as shown in FIG. 7, a perforating gun, generally identified by reference numeral 110, may comprise a number of charge arrangements (two shown in the present example) which each include a number of individual charges 112, 114 mounted within a body 116. The charge arrangements are confined to separate concentric regions 116 a, 116 b of the body. In the exemplary embodiment shown in FIG. 7, a multiple stage cycle may be used to establish multiple perforations along a length of a wellbore.

It should be understood that the embodiments described are merely exemplary and that various modifications may be made thereto without departing from the scope of the invention. For example, the perforating gun may be deployed in any suitable manner, such as on coiled tubing, on a tractor, pumped through the wellbore or the like. Additionally, a detonation signal may be transmitted in any suitable way, for example via fibre optics, wirelessly or the like. Further, any suitable arrangement and any suitable number of charge arrangements may be utilised. 

1. A perforating gun for use in a wellbore, comprising: a body configured to be displaced within a wellbore; and first and second charge arrangements mounted on the body and configured to be detonated independently of each other.
 2. The perforating gun according to claim 1, wherein the body is axially displaceable within a wellbore.
 3. The perforating gun according to claim 1, wherein the body is axially displaceable between detonation of the first and second charge arrangements.
 4. The perforating gun according to claim 1, wherein at least portions of the first and second charge arrangements are provided within a common axial length of the body.
 5. The perforating gun according to claim 1, wherein the first and second charge arrangements are configured to at least partially overlap in an axial direction relative to the body.
 6. The perforating gun according to claim 1, wherein at least portions of the first and second charge arrangements are confined to separate regions of the body.
 7. The perforating gun according to claim 6, wherein the separate regions of the body are arranged side-by-side.
 8. The perforating gun according to claim 6, wherein the separate regions of the body are defined by separate axially extending regions.
 9. The perforating gun according to claim 6, wherein the separate regions of the body are defined by separate annular or cylindrical regions of the body.
 10. The perforating gun according to claim 1, wherein portions of one charge arrangement at least partially circumferentially circumscribe portions of the other charge arrangement.
 11. The perforating gun according to claim 1, wherein the first and second charge arrangements are at least partially concentrically arranged, one inside the other, relative to the body.
 12. The perforating gun according to claim 1, wherein at least portions of the first and second charge arrangements are interspersed, and provided in a common region of the body.
 13. The perforating gun according to claim 1, wherein the first and second charge arrangements each comprise at least one charge.
 14. The perforating gun according to claim 13, wherein the at least one charge comprises an explosive material.
 15. The perforating gun according to claim 1, wherein one or both of the first and second charge arrangements comprises a plurality of charges.
 16. The perforating gun according to claim 1, comprising additional charge arrangements.
 17. The perforating gun according to claim 1, comprising first and second firing heads associated with the first and second charge arrangements, respectively.
 18. The perforating gun according to claim 17, wherein each firing head is independently detonates a respective charge arrangement.
 19. The perforating gun according to claim 17, wherein one or both of the first and second firing heads are mounted on or relative to the body.
 20. The perforating gun according to claim 1, comprising a controller for controlling detonation of one or both of the first and second charge arrangements.
 21. The perforating gun according to claim 20, wherein the controller comprises a receiver for receiving a signal from a remote location, the signal being associated with detonation instructions.
 22. The perforating gun according to claim 20, wherein the controller comprises a timer for initiating detonation of one or both of the first and second charge arrangements following a predetermined elapsed time.
 23. The perforating gun according to claim 22, wherein the timer is started in response to a predetermined event, wherein the predetermined event includes at least one of reaching a required depth, exposure to one or more predetermined conditions and in response to receipt of a signal.
 24. The perforating gun according to claim 22, wherein the timer is started in response to detonation of one of the first and second charge arrangements, permitting the charge arrangements to be detonated sequentially, separated by a predetermined elapsed time.
 25. The perforating gun according to claim 1, adapted to be mounted on a displacement arrangement for moving the perforating gun within a wellbore.
 26. The perforating gun according to claim 25, wherein the displacement arrangement comprises an elongate member secured to the perforating gun.
 27. The perforating gun according to claim 26, wherein the elongate member comprises at least one of wireline and coiled tubing.
 28. The perforating gun according to claim 26, wherein the elongate member establishes communication between the perforating gun and a remote location.
 29. The perforating gun according to claim 25, wherein the displacement arrangement comprises an autonomous displacement arrangement which includes an onboard drive apparatus,
 30. The perforating gun according to claim 1, provided in a combination with a tool storage chamber.
 31. A method for perforating a well, comprising: locating a perforating gun having first and second charge arrangements mounted on a body within a wellbore; and independently detonating the first and second charge arrangements.
 32. The method according to claim 31, comprising axially displacing the perforating gun between detonation of the first and second charge arrangements.
 33. The perforating gun according to claim 13, wherein the at least one charge comprises one or more projectiles.
 34. The perforating gun according to claim 30, wherein the perforating gun is manipulated within the tool storage chamber to be configured between a storage position and a deployed position. 